As the temperatures and pressures of well completions continue to increase, the hanging performance ratings for liner hangers and hold down slips will have to be improved to meet customer requirements and stay competitive in the high pressure high temperature market. One area of improvement for these anchoring systems is to improve the hanging capacity of the slip. Current liner hanger and hold down slips are machined as a single component resulting in a constant slip thickness. The slip thickness dictates the amount of radial overlap (bearing area) between the slip and slip seat when the slips are set downhole. Thus, the slip thickness limits the hanging performance of the anchor system. The slip thickness is limited by the drift requirements of the wellbore and by the body outside diameter needed to meet the pressure and tensile ratings. This prevents the improvement of hanging performance by simply increasing slip thickness. To improve the hanging performance of the slips, the proposed invention comprises a novel slip design that allows the effective slip thickness to be increased down hole. The increased effective thickness will increase the available bearing area improving the hanging performance of the slip. The simplest embodiment is a segmented slip design. Here the slip is comprised of multiple segments whose thickness meets the drift requirements when retracted for running in the hole, and when the down hole position is reached the effective thickness is increased by compressing the segments together. In addition to improving the hanging capacity, the proposed invention will allow for greater radial expansion of the slips.
In the past some of the slip designs have tried to extend the reach of a slip by using a combination of ramps as illustrated in U.S. Pat. Nos. 3,420,306 and 7,431,096. However, simply sliding a slip on a plurality of slopes to get enhanced radial extension does not increase the slip holding capacity as the ramps are not interlocking to function as a unitary structure so that the effective thickness of the slip itself is not effectively increased for additional carrying capacity. A traditional slip moving up a ramp is illustrated in U.S. Pat. No. 3,530,934.
Those skilled in the art will appreciate that the slip design of the present invention allows the slip assembly to articulate in a manner where the segments overlap each other while interlocking in a manner to effectively increase the slip thickness for enhanced load capacity while keeping the drift dimension of the tool sufficiently small for running in so that the tool can be rapidly deployed at the desired location. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.